U.S. Pat. No. 4,015,686 discloses a multi-stage lift which was in commercial production for many years. In this lift the stages comprise like extruded aluminum mast sections which interfit in front to back relation and are separated in the front to back direction by guide rollers. The lift stages are elevated by operation of a reeving system including a cable between a rear winch and a front carriage which passes over top and bottom pulleys in each extensible stage, a top pulley on the back stationary stage, and a pulley on the carriage.
U.S. Pat. No. 5,645,142 discloses a substantially similar multi-stage lift which has been in commercial production for many years. In this lift the stages comprise like extruded aluminum mast sections which interfit in front to back relation and are separated in the front to back direction by guide rollers. The lift stages are elevated by operation of a reeving system including a cable between a rear winch and a front carriage which passes over top and bottom pulleys in each extensible stage, a top pulley on the back stationary stage, and a pulley on the carriage.
The types of lifts disclosed above are lightweight and highly portable. They are typically manually-propelled, pushed or pulled by the machine operator to lift, position, and/or move moderately heavy materials from one location to another. They are also easily loadable into a pickup truck and commonly transported from one job site to another or to and from an equipment rental yard. These lifts are commonly operated by a dual-handled winch located at the rear of the machine.
Because the dual winch handles rotate and are not fixed in position, they are not ideal for steering the machine while maneuvering it around. Applicants have found that it is more ideal to have a fixed steering handle for manually moving the lift around the job site. Applicants have also found that such steering handle should be located at an ideal position for use as a fulcrum or pivot point for tipping the machine on its back when loading the lift into the back of a pickup truck or trailer for transportation of the machine to alternate locations. What has been found by the applicants is that the ideal position of the combined steering handle and adjustable loading fulcrum interfere with the ideal height of the winch handles that are used when raising and lowering materials.
U.S. Pat. No. 4,015,686 and FIG. 1 disclose an early version of these lifts. There are no steering handles available and the profile of the fixed height loading fulcrum is narrow enough so it will not interfere with the rotation of the dual winch handles while in use. The narrow fulcrum did not provide a means to steer the machine and it was also not very stable when lying on its back during vehicular transport due to the narrow profile of the fulcrum (which the machine rests on during transportation).
U.S. Pat. No. 5,645,142 discloses a subsequent version of these lifts. One can easily note the steering handle, which includes handle grips protruding outward on each side as well as a vertically rotatable design that allows the steering handle to be located in several different height positions relative to what is most comfortable for the individual operator's height for improved ergonomics. In addition, the vertically rotatable design serves two purposes as it also allows for the loading fulcrum to be adjusted relative to the height of a transport vehicle's tailgate or loading ramp. The vertically rotatable design consists of several holes aligned into an arc and a ball detent pin that can be removed and re-inserted into the various holes to adjust the overall height. This allows the operator to use the dual winch handles to raise and lower a load of materials and then raise the steering handles into an optimum position for maneuvering the machine (which in turn more than likely prevents the dual winch handles from moving through their complete range of motion—they would hit the steering handles). Once machine maneuvering is completed, the operator merely pulls the ball detent pin out of the height adjustment hole, lowers the steering handle to a position that would not interfere with the dual winch handles, and then proceeds to operate the winch again. When loading the machine into the back of a pickup truck the operator adjusts the loading fulcrum to an ideal height, keeping the loading wheels of the fulcrum as close as possible to the tailgate height of the pickup truck to make loading easy and more ergonomic. Because the loading fulcrum can be rotated out of the way of the dual winch handles, it can be made at a wider profile to provide a wider stance for improved stability of the machine during transport.
The vertically rotatable design of the combination steering handle and loading fulcrum was somewhat of a breakthrough at the time (nearly 20 years ago) but it has not been improved upon. Although the original design provides inherent improvements compared to prior iterations, it also requires the operator to continually remove and re-insert a ball detent pin manually, each time an adjustment of the combined steering handles and fulcrum is made. The ball detent and adjustment holes can eventually become corroded with rust and can sometimes become very difficult or impossible to remove. The ball detent pin is attached to the machine by a lanyard which is also prone to rust and eventual breakage, allowing the ball detent pin to be separated from the machine and to get lost on the job site.